Jump to somewhere after 5 minutes and watch to about 7:23.
If you're skeptic, try it out some time lol. Anyone that has seriously used one, and didn't really know how to use it, will say that the rest of the night wasn't too pleasant.
Yes, it does take more then one person to do.
Yes, sometimes its nothing bad and nothing happens. But most times, something does happen, one way or another, big or small.
If you did try it and only asked yes/no or any other simple questions like "What's your name? How old are you?" so on so forth, that's just lame. If you said "Hey make the lights flicker on and off if you're real" sometimes, if not most times, it does happen.
Lol I guess this goes for anyone else xD. I'm not crazy-ish for nothing you know.